Hi folks,
   Thanks for all your tremendous help. The leak is fixed, I just got home
to Brooklyn with no problems, and none of this could've been done without
your help.
   I found the O-ring at a dealer in Warington PA, it looked very different
from what it replaced: Not gray as some had mentioned in reply posts, but
much beefier than the original and with two tab-like protrusions on the
inner circumference that  that grabbed onto little barbs on the mating face
of the oil cooler.  Anyway- it seems to have done the trick, and I've
lightened the oil weight from 20w50 to 10w40, which makes the cold starts a
lot easier.

   Thanks so much to this list for bailing me out again!

-Matt Sutton
88 GL
Brooklyn NY